Popup refactor

1. Move all style properties to widget.tss
2. Create close button dynamicaly to make widget more independence
3. Cleanup
note that this may fail if some of the children is platform independant (as platform="ios" or platform="android). There is a titanium bug where children exists but is null (for that reason the original code continues if children does not exists). Also, javascript for loop performs quite faster than map function. Please refer to any benchmark.